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Search results for: dc micro grid
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Growth Orientation and the Profile of Micro-Entrepreneurs From the Pomorskie Province
PublicationThe article begins with the presentation of the concept of Entrepreneurial Orientation. Entrepreneurial Orientation assumes that some enterprises, regardless of size, behave in an entrepreneurial way and are proactive, innovative and willing to take risks. The relationships between Entrepreneurial Orientation and the results of enterprises are also subject to research, although its results are not clear – mainly due to the different...
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Design Analysis of Micro Gas Turbines in Closed Cycles
PublicationThe problems faced by designers of micro-turbines are connected with a very small volume flow rate of working media which leads to small blades’ height and high rotor speed. In the case of gas turbines this limitation can be overcome by the application of a closed cycle with very low pressure at the compressor inlet (lower than atmospheric pressure). In this way we may apply a micro gas turbine unit of accepted efficiency to work...
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Creating Dynamic Maps of Noise Threat Using PL-Grid Infrastructure
PublicationThe paper presents functionality and operation results of a system for creating dynamic maps of acoustic noise employing the PL-Grid infrastructure extended with a distributed sensor network. The work presented provides a demonstration of the services being prepared within the PLGrid Plus project for measuring, modeling and rendering data related to noise level distribution in city agglomerations. Specific computational environments,...
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Resonant DC link inverters for AC motor drive systems – critical evaluation
PublicationIn this survey paper, resonant and quasiresonant DC link inverters are reexamined for AC motor drive applications. Critical evaluation of representative topologies is based on simulation and waveform analysis to characterize current/voltage stress of components, control timing constraints and feasibility. A special concern over inverter common-mode voltage and voltage gradient du/dt limitation capacity is discussed for motor bearing...
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Domestic ORC micro-CHP combined with a commercial gas boiler
PublicationThe chapter presents the results of experimental studies conducted during the launch of the first in Poland demonstration prototype of the micro ORC coupled to a domestic gas boiler. The accomplished studies indicated the possibility for the ORC module to work with such boiler (autonomous source of heat) with a prototype single-stage axial micro turbine as the expansion machine. Confirmation of that fact has been delineated in...
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Tripping of F-type RCDs for sinusoidal residual current with superimposed smooth DC component
PublicationRecent trends in green energy development make that photovoltaics and electric vehicles are applied on an increasing scale. In both photovoltaic and electric vehicle charging installations, a significant value of DC component of the earth fault current may appear, which is a challenge, in particular, for commonly used residual current devices (RCDs). This paper presents results of the laboratory test on the operation of F-type...
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Nonlocal Models of Plates and Shells with Applications in Micro- and Nanomechanics
PublicationNowadays, the use of small-scale structures in micro/nanomachines has become more and more widespread. The most important applications of such small-sized parts are in micro-electro-mechanical systems (MEMS) as well as nano-electro-mechanical systems (NEMS) as actuators, sensors, energy harvesters. For example, nanosensors are nanoscale devices that measure physical quantities and convert these to signals that can be detected and...
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Ac and dc conductivities in v2o5-p2o5 glasses containing alkaline ions
PublicationWe investigated the ac and dc conductivity in 50V2O5-(50 − x)P2O5-xA2O (A = Li, Na, K) glasses as a function of temperature. The measurements were carried out in the frequency range from 10−4 to 107 Hz. For all compositions, the dc conductivity decreased with the increasing alkali ion content. The decrease in conductivity was more pronounced for larger alkali ions. The ac conductivity exhibited a universal dynamic response: σac...
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Dwukierunkowy przekształtnik 4L-DC z aktywną regulacją napięć w obwodzie pośredniczącym
PublicationW artykule opisano model laboratoryjny i wyniki badań dwukierunkowego symetrycznego (ang. Back-to-Back) przekształtnika 4L-DC (ang. Four Level Diode Clamped) z dwukierunkowym dwustopniowym przetwarzaniem energii (połączenie typu ang. Back-To-Back). W celu równoważenia i regulacji napięć kondensatorów w obwodzie pośredniczącym układu zastosowano dwa trójpoziomowe przerywacze DC-DC sterowane synchronicznie metodą modulacji PO-PWM...
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Output voltage, current and DC-link voltages under SVPWM, experimental results
Open Research DataThe dataset contains the experimental results of the project: A universal algorithm of space vector pulse width modulation for three-level three and multi-phase NPC inverters with DC-link voltage balancing. The output line-to-line voltage, output current and DC-link voltages were included. The comparison studies between proposed Space Vector Pulse-Width...
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Output voltage, current and DC-link voltages under SPWM, experimental results
Open Research DataThe dataset contains the experimental results of the project: A universal algorithm of space vector pulse width modulation for three-level three and multi-phase NPC inverters with DC-link voltage balancing. The output line-to-line voltage, output current and DC-link voltages were included. The Carrier-Based Pulse-Width Modulation (CBPWM) technique was...
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Reactive deposition of TiNx layers in a DC-magnetron discharge
PublicationTiNx layers have been deposited in 'balanced mode' and 'unbalanced mode' of a reactive DC-magnetron plasma (carrier gas argon, reactive gas nitrogen) under different conditions. Discharge power and reactive gas flow have been varied. The layers have been examined by X-ray photoelectron spectroscopy (XPS), X-ray reflectometry (XR), and spectroscopic ellipsometry (SE). The results of the layer analyses were combined with plasma investigations...
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Knowledge management implementation in small and micro KIBS : A categorization
Publicationhe main goal of the paper is to provide a statistical categorization of small and micro knowledge-intensive business service (KIBS) companies, based on their knowledge management (KM) attitude. Since knowledge is the main production factor and output of these companies, it is essential to achieve a better understanding of how they manage this resource. A questionnaire-based survey was conducted on a sample of Polish small and micro...
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The Application Of A Noise Mapping Tool Deployed In Grid Infrastructure For Creating Noise Maps Of Urban Areas
PublicationThe concept and implementation of the system for creating dynamic noise maps in PL-Grid infrastructure are presented. The methodology of dynamic acoustical maps creating is introduced. The concept of noise mapping, based on noise source and propagation models, was developed and employed in the system. The details of incorporation of the system to the PL-Grid infrastructure are presented. The results of simulations performed by...
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RCDs Tripping in the Range from DC to AC 50 kHz for Slowly Rising Residual Current
PublicationThe wide use of power electronic converters means that in many low-voltage systems earth fault currents containing components from DC to AC of various frequencies have to be taken into account. Due to the tendency to increase the modulation frequency in converters, components of higher frequencies may be in the order of several tens of kilohertz. Therefore, it is very important to verify the behavior of devices for protection against...
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Impact of dielectric deterioration on the conducted EMI emissions in the DC-DC boost converter
PublicationW artykule przedstawiono wpływ starzenia kondensatorów elektrolitycznych na poziom zaburzeń elektromagnetycznych generowanych przez układ podwyższający napięcie w oparciu o metody symulacyjne oraz cyfrowe przetwarzanie sygnału (filtracje Wienera). Wyniki przedstawiono w formie widm zaburzeń generowanych przez układ oraz transmitancji pomiędzy źródłem zaburzeń a zaburzeniami. (Wpływ starzenia się dielektryków na poziom zaburzeń...
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Step-Up DC/DC Converters With Cascaded Quasi-Z-Source Network
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APPLICATION OF INFRARED THERMOGRAPHY TO NON-CONTACT TESTING OF AD/DC POWER SUPPLY
PublicationTesting of AC/DC power supplies using the thermography was carried out in order to assess their assembly and operation correctness before launching them on the market. The investigation was carried out for 17 AC/DC power supplies which passed the standard tests (measurements of their basic parameters and characteristics). The investigation consisted of two steps. In the first step the dispersion of temperature on power supply boards...
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Oversizing the photovoltaic generator capacity in a micro photovoltaic plant
PublicationA significant part of photovoltaic micro installations in Poland is characterized by photovoltaic generator oversizing in relation to the inverter. The idea of oversizing, however, still raises doubts among some plant owners. In the paper, the energy yield of installation with an oversized and not oversized photovoltaic generator is presented on selected examples, showing the legitimacy of oversizing.
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Electrical safety in low-voltage DC microgrids with B-type residual current devices
PublicationResidual current devices (RCDs) are most popular devices used in low-voltage installations for protection against electric shock and fire. In cases of high risk of electric shock the application of RCDs is mandatory. Currently, the spread of local direct current (DC) microgrids is widely considered. This creates new challenges for protective systems, in particular those based on RCDs. The main purpose of the research is to test...
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Effect of Flow Normalization in Micro-Pin-Finned Heat Sink: Numerical Study
PublicationThe micro-pin-fin heat sink (MPFHS) is widely employed for the heat transfer enhancement of microchannel heat sinks. In the current paper, the effect of flow normalization on the thermohydraulic performance of micro-pin-finned heat sinks is studied numerically. Two geometries of MPFHSs, the conventional design micro-pin-fin heat sink (CD-MPFHS) with a uniform-width micro pin fin and the proposed design micro-pin-fin heat sink (PD-MPFHS)...
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Transportable, Portable and Micro Gas Chromatographs
PublicationSignificant benefits can be obtained by miniaturization of conventional benchtop gas chromatographs. The attractive features arising from miniaturization include low-power requirements, low heat capacity of separation columns, low consumption of mobile phase, enhanced performance, higher portability, and easily coupling to detectors and secondary chromatographic systems. In separation sciences, including gas phase separations,...
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SiC-Based Power Electronic Traction Transformer (PETT) for 3 kV DC Rail Traction
PublicationThe design of rolling stock plays a key role in the attractiveness of the rail transport. Train design must strictly meet the requirements of rail operators to ensure high quality and cost-eective services. Semiconductor power devices made from silicon carbide (SiC) have reached a level of technology enabling their widespread use in traction power converters. SiC transistors oering energy savings, quieter operation, improved reliability...
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High Frequency Harmonics Emission of Modern Power Electronic AC-DC Converters
PublicationModern AC/DC converters with bidirectional power flow employing PWM boost topology generate harmonic distortions of input current in relatively high frequency range tightly related to modulation carrier frequency. These frequencies and its multiples in typical applications are usually located in frequency range from single up to several of kHz. Increased harmonic emission in this frequency range can easily and harmfully influence...
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Reducing common mode voltage and bearing currents in quasi - resonant DC - link inverter
PublicationIn the paper, a concept of separation of an inverter-fed induction motor drive from its mains supply by two transistor switches inserted in the dc-link circuit is reexamined based on the proposed parallel quasi-resonant dc-link inverter (PQRDCLI). The objective of the paper is to show an advantage of the proposed topology in limiting high frequency common mode voltage and bearing currents. In the laboratory setup, an induction...
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Big Data Paradigm Developed in Volunteer Grid System with Genetic Programming Scheduler
PublicationArtificial intelligence techniques are capable to handle a large amount of information collected over the web. In this paper, big data paradigm has been studied in volunteer and grid system called Comcute that is optimized by a genetic programming scheduler. This scheduler can optimize load balancing and resource cost. Genetic programming optimizer has been applied for finding the Pareto solu-tions. Finally, some results from numerical...
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Techniki audytowania zabezpieczeń sieci bezprzewodowej z wykorzystaniem systemów klasy grid
PublicationZaprezentowano efektywne zasady weryfikacji zabezpieczeń sieci bezprzewodowych z wykorzystaniem oprogramowania Back/Track w dystrybucji systemu Linux. Omówiono algorytmy RC4, MIC i AES, które wspierają techniki zabezpieczeń WEP, WPA i WPA2 wchodzące w skład protokołu IEEW 802.11. Zamieszczano także opis wykorzystania systemu rozproszonego Comcute o architekturze typu grid do prowadzenia audytu bezprzewodowej sieci.
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Nano-Micro Letters
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Micro and Macro Marketing
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Micro and Nano Engineering
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Micro & Nano Letters
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Meta-computations on the CLUSTERIX Grid
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Essentials of micro and macroeconomics - Summer 2024
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Grid-Forming Operation of Energy-Router Based on Model Predictive Control with Improved Dynamic Performance
PublicationThe focus of this study is on the grid-forming operation of the Energy Router (ER) based on Model Predictive Control (MPC). ER is regarded as a key component of microgrids. It is a converter that interfaces the microgrid (s) with the utility grid. The ER has a multiport structure and bidirectional energy flow control. The ER concept can be implemented in Nearly Zero-Energy Buildings (NZEB) to provide flexible energy control. A...
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Application of the X-ray micro computed tomography to the analysis of the structure of polymeric materials
PublicationIn this paper the application of X-ray micro-computed tomography (micro-CT) as a non-destructive testing method of polymeric materials is presented. Increasing applicability of polymers in variedend-use industries such as automotive, building and construction, consumer goods, and packaging is propelling the growth of the global polymer processing market. However, controlling of the polymer structure is one of the most important...
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Engineering education for smart grid systems in the quasi-industrial environment of the LINTE^2 laboratory
PublicationSmart grid systems are revolutionising the electric power sector, integrating advanced technologies to enhance efficiency, reliability and sustainability. It is important for higher education to equip the prospective smart grid professional with the competencies enabling them to navigate through the related complexities and drive innovation. To achieve this, interdisciplinary education programmes are necessary, addressing inter...
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Integration of electric vehicle into smart grid: a meta heuristic algorithm for energy management between V2G and G2V
PublicationRecently, Electric Vehicles (EV) have been providing fast response and substantial progress in the power generation model. Further, EVs are exploited as adaptable Energy Storage Systems (ESSs) and show a promising performance in ancillary service markets to increase the demand of Smart Grid (SG) integration. The expansion of Vehicle-to-Grid concept has created an extra power source when renewable energy sources are not available....
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Four Level Diode-Clamped Back-To-Back Converter with Active DC Link Voltage Control
PublicationThis article presents the design and control of 4L-DC back-to-back converter. To solve the DC link voltage balancing problem in four-level converter a new three-level double chopper topology based on PO-PWM modulation was designed and successfully tested. Also, the paper describes two phase space vector pulse width modulation 2P-SVPWM based on the shape function of finite elements. The control structure with modified Dead-Beat...
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New high-gain step-up DC/DC converter with high-frequency isolation
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Unidirectional thyristor-based DC-DC converter for HVDC connection of offshore wind farms
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Power Hardware In-the-Loop validation of DC-DC power converter for offshore wind energy
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Conducted EMI mitigation in switched mode DC-DC converters by spread spectrum techniques
PublicationW artykule przedstawiono skuteczność technik rozpraszania widma do ograniczenia emisji przewodzonej EMI dla szeregowego przerywacza napięcia. Badania porównawcze zostały wykonane laboratoryjnie za pomocą generatora funkcyjnego, miernika zaburzeń i sieci sztucznej. Analiza otrzymanych wyników wykazała, szczególnie korzystne do 20 dB, ograniczenie charakterystyki napięcia emisji przewodzonej dla losowej modulacji częstotliuwości...
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Micro‑ and nano‑ bentonite to improve the strength of clayey sand as a nano soil‑improvement technique
PublicationNano-additives results in the formation of nano-cementation (NC). This process is recently used to improve the durability of various building materials. NC used to improve the strength of untreated soil materials, also known as nano soil-improvement (NSI). In few years, the role of nano-additives in various types of soils were developed. In this research, the role of micro- and nano- size of bentonite as soil stabilizer was evaluated...
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Shear fracture of longitudinally reinforced concrete beams under bending using Digital Image Correlation and FE simulations with concrete micro-structure based on X-ray micro-computed tomography images
PublicationThe paper presents experimental and numerical investigations of the shear fracture in rectangular concrete beams longitudinally reinforced with steel or basalt bar under quasi-static three point bending. Shear fracture process zone formation and development on the surface of beams was investigated by Digital Image Correlation (DIC) whereas thorough analyses of 3D material micro-structure, air voids, width and curvature of shear...
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Low Frequency Conducted Emissions of Grid Connected Static Converters
PublicationPulse-width modulated rectifiers are nowadays commonly used for AC to DC power conversion. PWM rectification technology is very effective and allows for bidirectional power flow with the possibility of power factor improvement and low-order harmonic emission limitation. Unfortunately, employed PWM boost topology results with generation of input current harmonic distortions in a frequency range tightly correlated to modulation frequency....
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Creating dynamic maps of noise threat using pl-grid infrastructure; materiały konferencyjne
PublicationThis paper presents functionality and operation results of the system for creating dynamic maps of noise thread with the use of the PL-Grid infrastructure integrated with distributed sensors network for measuring, modeling and rendering noise level distribution. The work presented provides a demonstration of the services being prepared within the PLGrid Plus project. Specific computational environments, so called domain grids,...
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Discrete Modelling of Micro-structural Phenomena in Granular Shear Zones
PublicationThe micro-structure evolution in shear zones in cohesionless sand for quasi-static problems was analyzed with a discrete element method (DEM). The passive sand failure for a very rought retaining wall undergoing horizontal translation towards the sand backfill was discussed. To simulate the behaviour of sand, the spherical discrete element model was used with elements in the form of rigid spheres with contacts moments.
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Changes on the Surface of the SiO2/C Composite, Leading to the Formation of Conductive Carbon Structures with Complex Nature of DC Conductivity
Open Research DataChanges on the Surface of the SiO2/C Composite, Leading to the Formation of Conductive Carbon Structures with Complex Nature of DC Conductivity
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Space-vector pulsewidth modulation for a seven-level cascaded H-bridge inverter with the control of DC-link voltages
PublicationThe control strategy of DC-link voltages for a seven-level Cascaded H-Bridge inverter is proposed in this paper. The DC-link voltage balancing is accomplished by appropriate selection of H-Bridges and control of their duty cycles in Space-Vector Modulation (SVM) algorithm. The proposed SVM method allows to maintain the same voltage level on all inverter capacitors. Regardless of the balancing function, the...
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Electrochemicalsynthesis of 3D nano-/micro-structured porous polypyrrole
PublicationIn this work, electrosynthesis of electroactive, 3D nano-/micro-structured porous polypyrrole film is presented. The PPy film was synthesized potentiostatically in a one-step process from aqueous solution of pyrrole and lithium perchlorate. The growth mechanism of such structure included: the formation of typical globular PPy film, followed by the formation of the PPy fibers, which then took part in the formation of 3D highly porous...